Never had random reboots or graphical artifacts on screen before on OSX but my iMac has been very unstable since the High Sierra update. I’m lucky I’m not using

Never had random reboots or graphical artifacts on screen before on OSX but my iMac has been very unstable since the High Sierra update. I’m lucky I’m not using that machine for work or I would be raging on a daily basis. I’m not an “Apple are doomed”-er but this is the poorest Apple OS release since the black screen of death that plagued iOS8. You seem to generally get about 3 years of use from an iOS device before the CPU can’t really keep up with the OS updates. I couldn’t recommend upgrading an iPhone 6 to iOS 11 as my wife’s 6 Plus has basically become unusable. Maybe part of the problem is that no-one in Cupertino will be using a 3-4 year old iPhone or a 2012 Mac on a daily basis?